1. Field of the Invention
The present invention relates to a lens drive apparatus built in an image pickup apparatus. More specially, the present invention relates to a lens drive apparatus which moves a lens in an optical axis direction by use of a cam member.
2. Description of the Related Art
Recently, an image pickup apparatus, such as a still camera or a camera built in a mobile phone, has been smaller in size significantly. There is such an image pickup apparatus which includes a lens drive apparatus moving a lens to a focused point in accordance with the position of the object. Thus, the lens drive apparatus which has a smaller size and a high focus accuracy is required.
Document 1 (Japanese Utility Model Application Publication No. 5-61713) discloses a lens drive mechanism which moves a lens in the optical axis direction by use of a cam member. In this lens drive mechanism, the lens can be driven with a simple structure having a cam member. Further, this lens drive mechanism has plural switches for detecting a position of the cam member. The lens drive mechanism recognizes the initial position or a partway position by using these switches, thereby adjusting the focus with high accuracy. More specially, this lens drive mechanism has a mechanical switch for detecting the initial position of the cam, and a photo interrupter (optical switch) for detecting a substantial middle position of driving range of the cam so as to detect the position of the cam.
The above lens drive mechanism disclosed in Document 1 has a simple structure, since the cam structure drives the lens. However, the above lens drive mechanism detects the position of the cam member by using the plural switches. This requires a space for arranging the switches within the mechanism, thus enlarging the structure of the lens drive mechanism. In accordance with this, plural expensive switches are used, thereby causing a problem of increase in the manufacturers' cost.